- Email: [email protected]
Building a stratigraphy of fluvial sediments in the Budejovice Basin (Czech Republic) based on absolute ages - first OSL-ages of the Vltava river terraces
Abstracts / Quaternary International 279-280 (2012) 121–232
thermal regime of this lake. Most pronounced were the changes in the chemocline, which decreased about 10 m compared to the 1960ies, and for water level, which decreased about 4 m over the last 4 years. While summer air temperature had been particularly cold in this area in the 1960ies, the summer of 2007 was the warmest on the centennial record. These changes are tremendous and cannot be explained by changes in precipitation. We hypothesize that the permafrost melting in the catchment area is a major driver for the changes in water level and chemocline. We observed that the pathways of water changed over the last few years. Currently we investigate the sediment records of this lake in order to gain a long term perspective, and to study how permafrost and thermokarst processes have affected this lake during warm periods in the past. A RECORD OF LATE GLACIAL-HOLOCENE ENVIRONMENTAL CHANGE FROM TWO ADJACENT BIOPHYSICAL REGIMES IN THE SOUTHERN CAPE, SOUTH AFRICA Peter Holmes. University of the Free State, South Africa
205
Quaternary deposits which demonstrably predate MIS 11 have not yet been recognised anywhere on the Islands. This absence is attributed to erosion during the widespread marine transgression during the exceptionally long interglacial of MIS 11. Thick blanket peat covers at least 50% of the Islands’ surface. The majority of this peat is of Last Interglacial to Holocene age, but there are also discontinuous sequences extending back to MIS 11. Pollen records obtained from these peat deposits have been used to investigate vegetation change in the Islands over the last w400 ka. These indicate that vegetation changes in the Chatham Islands over the Quaternary occur in response to changes in moisture availability as well as temperature. NEW RESULTS ON THE TRANSITION FROM THE MAGDALENIAN TO THE FEDERMESSERGRUPPEN IN WESTERN GERMANY Joerg Holzkaemper. University of Cologne, Institute of Prehistoric Ar, Germany E-mail address: [email protected]
E-mail address: [email protected]
Over Quaternary timescales it is frequently difficult to isolate the environmental processes driving phases of fluvial aggradation and incision within drainage basins. Vegetation cover is known to affect sediment delivery, deposition and storage within catchments, but it is often difficult to unambiguously identify direct climate responses. Here, we compare two comparably aged sequences in similar geological and pedological settings, but within different biophysical regimes, to directly address commonalities and differences in the resulting sedimentary archives. Two valleybottom sediment fill sequences along the Kammanassie and Louterwater Rivers in the southern Cape, South Africa, reveal rare depositional sequences of w8.5 m and w6 m respectively. The sequences have been exposed by Late Holocene fluvial incision. The first site, situated in the rain shadow of the Kouga Mountains, receives all-year-round rainfall of w220 mm per annum and is under Succulent Karoo shrub vegetation. The second site, w80 km east of the first, also receives year-round rainfall (w390 mm per annum) with pronounced autumn and late-winter maxima and is under Fynbos vegetation. Table Mountain Group sandstone forms the predominant geology at both sites, and local (derived) soils are sandy and nutrient-poor. Logging of exposed sediment profiles at both sites, and systematic sampling to investigate their sedimentological, stable isotope and palynological characteristics was undertaken. Both sites reveal interdigited inorganic (gravel and sand) and organic-rich sediments. Temporal control established via radiocarbon (14C) and optically stimulated luminescence (OSL) dating confirms that both sites preserve records extending back to the Late Glacial (c.12 000 years ago). Results from each site are presented and compared.
Rapid climate changes within the Late Last Glacial in Western Central Europe strongly influenced the ecosystem and put hunter-gatherer communities under ecological pressure. The relation between changing environments and human behaviour is investigated diachronically by the project “Analysis of Migration Processes due to Environmental Conditions between 40,000 and 14,000 BP in the Rhine-Meuse area” of the CRC 806 “Our way to Europe – Culture-Environment Interaction and Human Mobility in the Late Quaternary”. Present field investigations geographically focus on the federal state of North Rhine-Westphalia, and chronologically concentrate on the partial resettlement of that region after the LGM. Few Late Magdalenian sites (after 15,500 calBP) have been located on the Low Mountain range of the Rhenish Massiv and the southern Lower Rhine embayment, whereas the Westphalian Bay shows no settlement traces so far. One major objective of the project is to find possible explanations for the typical Magdalenian pattern of distinct site concentrations adjoining areas without settlement traces. In this regard, a geoarchaeological approach on a regional scale is applied. Preliminary results argue for a considerably late resettlement of the entire region during the transition period between the Magdalenian and the Federmessergruppen, following a phase of less intense land use. The assemblages show influences by both the Hamburgian and Creswellian and are similar to findings in the neighbouring Netherlands. At the moment, it is believed that these sites date to the beginning of the Late Glacial warming. In order to set up a more reliable chronostratigraphy for this transition period, geoarchives in the surrounding of the sites in North Rhine-Westphalia will be analysed applying sedimentological, geochemical and luminescence methods.
THE QUATERNARY HISTORY OF THE CHATHAM ISLANDS, EASTERN OUTPOST OF NEW ZEALAND: INSIGHTS INTO QUATERNARY TERRESTRIAL ENVIRONMENTAL CHANGE IN A REMOTE OCEANIC SETTING
BUILDING A STRATIGRAPHY OF FLUVIAL SEDIMENTS IN THE BUDEJOVICE BASIN (CZECH REPUBLIC) BASED ON ABSOLUTE AGES FIRST OSL-AGES OF THE VLTAVA RIVER TERRACES
Kat Holt. Massey University, New Zealand
E-mail address: [email protected]
Dana Homolová. University of Vienna, Austria E-mail address: [email protected]
The Chatham Islands preserve the easternmost occurrence of terrestrial Quaternary strata of the New Zealand subcontinent and provide great potential for a range of palaeoenvironmental and tectonic studies relevant to both short- and long-term timescales in the southwest Pacific region. The subdued topography (<300 m a.s.l.) and oceanic location have resulted in a climate that is strongly moderated by the surrounding ocean. The Quaternary record of the Islands comprises mostly terrestrial deposits, dominantly peat and aeolian sand or loessial deposits. The Islands lie w900 km downwind of mainland New Zealand, and as a consequence volcanic ashes (tephra) derived from the exceptionally productive Taupo Volcanic Zone, as well as pollen from New Zealand vegetation, have been deposited in the Islands throughout the Quaternary. Both the tephras and the long-distance pollen facilitate accurate correlation between pollen and other proxy records from the Chatham Islands with those from the North and South Islands, and the wider Southwest Pacific region. To date,
The Budejovice Basin, situated in Southern Bohemia (Czech Republic) is a fault-bounded sedimentary basin with a multiple subsidence history overlying the Variscan crystalline basement of the Bohemian Massif. The Vltava River, crossing the basin from the south to the north, accumulated terrace bodies of different horizontal and vertical extent during the whole Pleistocene and probably further back in the past. According to the scheme used in most European regions, influenced by the Pleistocene glacial cycles, these terraces were assigned by most scientists to the 4 or 5 main alpine glacial periods. Due to the fact that the catchment area of the Vltava River was not glaciated during the Pleistocene, this correlation is not straightforward as terraces are not connected to moraine bodies like in the Alps. Since there is so far no data concerning the numerical age of the Quaternary sediment cover in the research area, OSL-dating is the key method in building a late Pleistocene stratigraphy of the sediment fill of the Budejovice Basin. Recent work focused on the mapping and dating of Pleistocene river terraces in the vicinity of Hluboká nad Vltavou in order to
206
Abstracts / Quaternary International 279-280 (2012) 121–232
establish a chronology of terrace formation in this area. Currently available data is derived from about 100 outcrops and hand drillings and 17 shallow boreholes, the stratigraphic correlations rely on 19 OSL ages. First results show five terrace levels in the crystalline basement and at least four levels in the Budeovice Basin. The uppermost terrace levels are out of the dating range of the method, but for the lower terraces, it was possible to create a consistent stratigraphy with ages ranging from about 80 ka to the Holocene. Further mapping and dating is planned to create an inventory of the terrace bodies in the Budejovice Basin and to correlate these with other European catchments of comparable extent. RECONSTRUCTING THE PLEISTOCENE AND HOLOCENE LANDSCAPE DEVELOPMENT AT THE NORTHWESTERN NEUSIEDLERSEE (AUSTRIA) – NEW SEDIMENTOLOGICAL AND PALAEOECOLOGICAL RESULTS Dana Homolová. University of Vienna, Austria E-mail address: [email protected]
The Neusiedlersee-region, situated southeast of Vienna at the border to Hungary, forms – due to its specific natural setting – a unique landscape and environment in central Europe. The whole region is characterized by a very long settlement history resulting from its warm and dry climate and from the presence of the lake Neusiedlersee. The main focus of this thesis is on reconstructing the landscape development of the northwestern Neusiedlersee-area during the Pleistocene and Holocene using field and laboratory methods. Our investigations cover geomorphological and pedological mapping as well as mapping and sampling of outcrops in the northeastern Leitha Mountains. Additionally, a 6 m deep drilling was conducted in the Joiser Seewiesen, a former sea floor of the lake Neusiedlersee. The laboratory analyses include grain size, pH-value, carbonate content, color as well as bulk and clay mineralogy. Additionally, malacological and palynological analyses as well as OSL-dating of the sediment cover have been done. The outcrops in the Leitha Mountains (Leithagebirge) reveal periglacial sediments as frost debris, solifluction layers, loess and ventifacts and in places, layers showing some attributes of palaeosols are present as well. These features indicate, that during the Pleistocene, this region belonged to the periglacial area. The malacological analysis of a loess outcrop revealed a unique mollusc fauna, indicating late Pleistocene cold and wet climatic conditions. Pollen found in old lake sediments from the drilling in the Joiser Seewiesen are also typical for the late Pleistocene, indicating a bigger extent of the Lake Neusiedlersee during that time. SOUTH CHINA SEA HYDROLOGICAL CHANGES OVER THE LAST MILLENNIUM Yan Hong. University of Science and Technology of China, China E-mail address: [email protected]
Tropical Pacific hydrology has widespread impacts on global climate. Although El Niño-Southern Oscillation (ENSO) variability, and thus the strength of Pacific Walker Circulation, greatly affects modern precipitation observed in the western tropical Pacific, over centennial through millennial timescales, hydrological changes in this region are almost exclusively attributed to north-south movement of the inter-tropical convergence zone (ITCZ). Here, we test this hypothesis with new hydrological reconstructions from Cattle Pond, Dongdao Island (w16 40'N, 112 44'E), in the central South China Sea, where rainfall variability is correlated to the Southern Oscillation Index (SOI) on multi-decadal time scales, and this variability is captured by downcore grain-size variations during the instrumental era. We extend these reconstructions to span the last millennia, and find that this site has consistently received less precipitation during the relatively warm period, AD 1000-1400 and AD 1850-2000, and more rainfall during the cool period (AD 1400-1850). Including our new records in a synthesis of published records from the tropical Pacific rules out north-south ITCZ migration as the dominant mechanism of hydrologic variability at our core site. Although ITCZ migrations may have indeed played an important role in controlling tropical Pacific hydrology, our results suggest that changes in Pacific Walker Circulation also profoundly influenced tropical hydrology over the last millennium.
CLIMATIC BACKGROUND ON THE EVOLUTIONAL PROCESS OF CHINESE CIVILIZATION Yetang Hong. Institute of Geochemistry, China E-mail address: [email protected]
Chinese civilization (CCZ) originates from the three ancient cultures, namely the Yellow River basin culture, Yangtze River basin culture and northern nomadic culture. The comparison between the chronology of Chinese dynasty and the Jinchuan peat cellulose d18O record shows that the evolutional process of CCZ occurred generally in the warmer climatic condition on centennial timescale. The Xia Dynasty, the first dynasty in the Chinese history, was established at 2070 BC that just points to a turning point from a decreasing to an increasing of temperature. In the warmer and drier Shang Dynasty ancient China completed transition from the Neolithic to Bronze Age, and created the Oracle bone script. The following around 800-year also was in the warmer and drier climate. Occurrence of the different philosophies, including Confucianism, Taoism, Legalism and Mohism, had laid the foundation for CCZ. In the Qin and Han Dynasties roughly corresponding to the Roman Warmer Period the unification of both Chinese characters and metrology had been completed. The world's first movable type technique, compass and powder used in war occurred in the Song Dynasty corresponding to the Medieval Warm Epoch of Europe. Abrupt climatic deterioration seems to be often liked to agricultural failures and instability in the ancient society. The peat record indicates a widespread climate abnormality from about 3000 to 2000 BC corresponding to the archaeological Longshan era. Both the Hongshan culture in the northern China and the Liangzhu culture in the lower reaches of Yangtze River collapsed to around 2200 BC. However the Yellow River basin culture in the late Longshan era had obviously contained the characteristics of both the nomadic culture and the Yangtze River basin culture, and eventually was developed into the unified CCZ marked by the establishment of the Xia Dynasty. NORTH ANDEAN FOREST DYNAMICS MIMICS GREENLAND ICE CORES: CHANGING VEGETATION, LAKE-LEVELS, GEOCHEMISTRY, AND SEDIMENT FLUX AT w50-YR RESOLUTION DURING THE LAST 284 KA Henry Hooghiemstra. University of Amsterdam / Institute for Biodiversity, Netherlands E-mail address: [email protected]
Pleistocene climate change is well documented in the marine LR04 benthic d18O stack record which serves as the standard for climate variability. Ice cores record climate change of the last part of the Pleistocene with stunning detail. Although land-based records of climate change often suffer from hiatuses and unsufficient time control some sedimentary basins keep archives of unprecedented high quality. Records from a new 60-m composite record from the Fúquene Basin (Colombia), reflecting the period 284-27 ka, are presented. Ca. 4600-point time series of pollen, elements and grain size fractions allow individual proxies to be interpreted in a multiproxy environment. A newly developed independent age model and correlations with marine and ice records place the evolution of Andean ecosystems in a global perspective. We compared the Fúquene record with the re-visited 2700-ka Funza-2 record form the Bogotá Basin (2100-point time series from a 586-m core). We concluded that vegetation change in the high Andes is mainly driven by obliquity (41 kyr) forcing. A modelling study showed that solar forcing alone cannot explain the observed temperature record hinting changing pCO2 is an important driver in the high tropical Andes. The life cycle of paleo-lake Bogotá is newly explored and discussed. CONTROL OF QUARRYING BY BEDROCK JOINTS Thomas Hooyer. University of Wisconsin-Milwaukee, United States E-mail address: [email protected]
The formation of overdeepened valleys and basins in glaciated terrain is the result of enhanced subglacial erosion that is likely dominated by quarrying. This process is thought to depend on slow growth of preexisting, isolated
thermal regime of this lake. Most pronounced were the changes in the chemocline, which decreased about 10 m compared to the 1960ies, and for water level, which decreased about 4 m over the last 4 years. While summer air temperature had been particularly cold in this area in the 1960ies, the summer of 2007 was the warmest on the centennial record. These changes are tremendous and cannot be explained by changes in precipitation. We hypothesize that the permafrost melting in the catchment area is a major driver for the changes in water level and chemocline. We observed that the pathways of water changed over the last few years. Currently we investigate the sediment records of this lake in order to gain a long term perspective, and to study how permafrost and thermokarst processes have affected this lake during warm periods in the past. A RECORD OF LATE GLACIAL-HOLOCENE ENVIRONMENTAL CHANGE FROM TWO ADJACENT BIOPHYSICAL REGIMES IN THE SOUTHERN CAPE, SOUTH AFRICA Peter Holmes. University of the Free State, South Africa
205
Quaternary deposits which demonstrably predate MIS 11 have not yet been recognised anywhere on the Islands. This absence is attributed to erosion during the widespread marine transgression during the exceptionally long interglacial of MIS 11. Thick blanket peat covers at least 50% of the Islands’ surface. The majority of this peat is of Last Interglacial to Holocene age, but there are also discontinuous sequences extending back to MIS 11. Pollen records obtained from these peat deposits have been used to investigate vegetation change in the Islands over the last w400 ka. These indicate that vegetation changes in the Chatham Islands over the Quaternary occur in response to changes in moisture availability as well as temperature. NEW RESULTS ON THE TRANSITION FROM THE MAGDALENIAN TO THE FEDERMESSERGRUPPEN IN WESTERN GERMANY Joerg Holzkaemper. University of Cologne, Institute of Prehistoric Ar, Germany E-mail address: [email protected]
E-mail address: [email protected]
Over Quaternary timescales it is frequently difficult to isolate the environmental processes driving phases of fluvial aggradation and incision within drainage basins. Vegetation cover is known to affect sediment delivery, deposition and storage within catchments, but it is often difficult to unambiguously identify direct climate responses. Here, we compare two comparably aged sequences in similar geological and pedological settings, but within different biophysical regimes, to directly address commonalities and differences in the resulting sedimentary archives. Two valleybottom sediment fill sequences along the Kammanassie and Louterwater Rivers in the southern Cape, South Africa, reveal rare depositional sequences of w8.5 m and w6 m respectively. The sequences have been exposed by Late Holocene fluvial incision. The first site, situated in the rain shadow of the Kouga Mountains, receives all-year-round rainfall of w220 mm per annum and is under Succulent Karoo shrub vegetation. The second site, w80 km east of the first, also receives year-round rainfall (w390 mm per annum) with pronounced autumn and late-winter maxima and is under Fynbos vegetation. Table Mountain Group sandstone forms the predominant geology at both sites, and local (derived) soils are sandy and nutrient-poor. Logging of exposed sediment profiles at both sites, and systematic sampling to investigate their sedimentological, stable isotope and palynological characteristics was undertaken. Both sites reveal interdigited inorganic (gravel and sand) and organic-rich sediments. Temporal control established via radiocarbon (14C) and optically stimulated luminescence (OSL) dating confirms that both sites preserve records extending back to the Late Glacial (c.12 000 years ago). Results from each site are presented and compared.
Rapid climate changes within the Late Last Glacial in Western Central Europe strongly influenced the ecosystem and put hunter-gatherer communities under ecological pressure. The relation between changing environments and human behaviour is investigated diachronically by the project “Analysis of Migration Processes due to Environmental Conditions between 40,000 and 14,000 BP in the Rhine-Meuse area” of the CRC 806 “Our way to Europe – Culture-Environment Interaction and Human Mobility in the Late Quaternary”. Present field investigations geographically focus on the federal state of North Rhine-Westphalia, and chronologically concentrate on the partial resettlement of that region after the LGM. Few Late Magdalenian sites (after 15,500 calBP) have been located on the Low Mountain range of the Rhenish Massiv and the southern Lower Rhine embayment, whereas the Westphalian Bay shows no settlement traces so far. One major objective of the project is to find possible explanations for the typical Magdalenian pattern of distinct site concentrations adjoining areas without settlement traces. In this regard, a geoarchaeological approach on a regional scale is applied. Preliminary results argue for a considerably late resettlement of the entire region during the transition period between the Magdalenian and the Federmessergruppen, following a phase of less intense land use. The assemblages show influences by both the Hamburgian and Creswellian and are similar to findings in the neighbouring Netherlands. At the moment, it is believed that these sites date to the beginning of the Late Glacial warming. In order to set up a more reliable chronostratigraphy for this transition period, geoarchives in the surrounding of the sites in North Rhine-Westphalia will be analysed applying sedimentological, geochemical and luminescence methods.
THE QUATERNARY HISTORY OF THE CHATHAM ISLANDS, EASTERN OUTPOST OF NEW ZEALAND: INSIGHTS INTO QUATERNARY TERRESTRIAL ENVIRONMENTAL CHANGE IN A REMOTE OCEANIC SETTING
BUILDING A STRATIGRAPHY OF FLUVIAL SEDIMENTS IN THE BUDEJOVICE BASIN (CZECH REPUBLIC) BASED ON ABSOLUTE AGES FIRST OSL-AGES OF THE VLTAVA RIVER TERRACES
Kat Holt. Massey University, New Zealand
E-mail address: [email protected]
Dana Homolová. University of Vienna, Austria E-mail address: [email protected]
The Chatham Islands preserve the easternmost occurrence of terrestrial Quaternary strata of the New Zealand subcontinent and provide great potential for a range of palaeoenvironmental and tectonic studies relevant to both short- and long-term timescales in the southwest Pacific region. The subdued topography (<300 m a.s.l.) and oceanic location have resulted in a climate that is strongly moderated by the surrounding ocean. The Quaternary record of the Islands comprises mostly terrestrial deposits, dominantly peat and aeolian sand or loessial deposits. The Islands lie w900 km downwind of mainland New Zealand, and as a consequence volcanic ashes (tephra) derived from the exceptionally productive Taupo Volcanic Zone, as well as pollen from New Zealand vegetation, have been deposited in the Islands throughout the Quaternary. Both the tephras and the long-distance pollen facilitate accurate correlation between pollen and other proxy records from the Chatham Islands with those from the North and South Islands, and the wider Southwest Pacific region. To date,
The Budejovice Basin, situated in Southern Bohemia (Czech Republic) is a fault-bounded sedimentary basin with a multiple subsidence history overlying the Variscan crystalline basement of the Bohemian Massif. The Vltava River, crossing the basin from the south to the north, accumulated terrace bodies of different horizontal and vertical extent during the whole Pleistocene and probably further back in the past. According to the scheme used in most European regions, influenced by the Pleistocene glacial cycles, these terraces were assigned by most scientists to the 4 or 5 main alpine glacial periods. Due to the fact that the catchment area of the Vltava River was not glaciated during the Pleistocene, this correlation is not straightforward as terraces are not connected to moraine bodies like in the Alps. Since there is so far no data concerning the numerical age of the Quaternary sediment cover in the research area, OSL-dating is the key method in building a late Pleistocene stratigraphy of the sediment fill of the Budejovice Basin. Recent work focused on the mapping and dating of Pleistocene river terraces in the vicinity of Hluboká nad Vltavou in order to
206
Abstracts / Quaternary International 279-280 (2012) 121–232
establish a chronology of terrace formation in this area. Currently available data is derived from about 100 outcrops and hand drillings and 17 shallow boreholes, the stratigraphic correlations rely on 19 OSL ages. First results show five terrace levels in the crystalline basement and at least four levels in the Budeovice Basin. The uppermost terrace levels are out of the dating range of the method, but for the lower terraces, it was possible to create a consistent stratigraphy with ages ranging from about 80 ka to the Holocene. Further mapping and dating is planned to create an inventory of the terrace bodies in the Budejovice Basin and to correlate these with other European catchments of comparable extent. RECONSTRUCTING THE PLEISTOCENE AND HOLOCENE LANDSCAPE DEVELOPMENT AT THE NORTHWESTERN NEUSIEDLERSEE (AUSTRIA) – NEW SEDIMENTOLOGICAL AND PALAEOECOLOGICAL RESULTS Dana Homolová. University of Vienna, Austria E-mail address: [email protected]
The Neusiedlersee-region, situated southeast of Vienna at the border to Hungary, forms – due to its specific natural setting – a unique landscape and environment in central Europe. The whole region is characterized by a very long settlement history resulting from its warm and dry climate and from the presence of the lake Neusiedlersee. The main focus of this thesis is on reconstructing the landscape development of the northwestern Neusiedlersee-area during the Pleistocene and Holocene using field and laboratory methods. Our investigations cover geomorphological and pedological mapping as well as mapping and sampling of outcrops in the northeastern Leitha Mountains. Additionally, a 6 m deep drilling was conducted in the Joiser Seewiesen, a former sea floor of the lake Neusiedlersee. The laboratory analyses include grain size, pH-value, carbonate content, color as well as bulk and clay mineralogy. Additionally, malacological and palynological analyses as well as OSL-dating of the sediment cover have been done. The outcrops in the Leitha Mountains (Leithagebirge) reveal periglacial sediments as frost debris, solifluction layers, loess and ventifacts and in places, layers showing some attributes of palaeosols are present as well. These features indicate, that during the Pleistocene, this region belonged to the periglacial area. The malacological analysis of a loess outcrop revealed a unique mollusc fauna, indicating late Pleistocene cold and wet climatic conditions. Pollen found in old lake sediments from the drilling in the Joiser Seewiesen are also typical for the late Pleistocene, indicating a bigger extent of the Lake Neusiedlersee during that time. SOUTH CHINA SEA HYDROLOGICAL CHANGES OVER THE LAST MILLENNIUM Yan Hong. University of Science and Technology of China, China E-mail address: [email protected]
Tropical Pacific hydrology has widespread impacts on global climate. Although El Niño-Southern Oscillation (ENSO) variability, and thus the strength of Pacific Walker Circulation, greatly affects modern precipitation observed in the western tropical Pacific, over centennial through millennial timescales, hydrological changes in this region are almost exclusively attributed to north-south movement of the inter-tropical convergence zone (ITCZ). Here, we test this hypothesis with new hydrological reconstructions from Cattle Pond, Dongdao Island (w16 40'N, 112 44'E), in the central South China Sea, where rainfall variability is correlated to the Southern Oscillation Index (SOI) on multi-decadal time scales, and this variability is captured by downcore grain-size variations during the instrumental era. We extend these reconstructions to span the last millennia, and find that this site has consistently received less precipitation during the relatively warm period, AD 1000-1400 and AD 1850-2000, and more rainfall during the cool period (AD 1400-1850). Including our new records in a synthesis of published records from the tropical Pacific rules out north-south ITCZ migration as the dominant mechanism of hydrologic variability at our core site. Although ITCZ migrations may have indeed played an important role in controlling tropical Pacific hydrology, our results suggest that changes in Pacific Walker Circulation also profoundly influenced tropical hydrology over the last millennium.
CLIMATIC BACKGROUND ON THE EVOLUTIONAL PROCESS OF CHINESE CIVILIZATION Yetang Hong. Institute of Geochemistry, China E-mail address: [email protected]
Chinese civilization (CCZ) originates from the three ancient cultures, namely the Yellow River basin culture, Yangtze River basin culture and northern nomadic culture. The comparison between the chronology of Chinese dynasty and the Jinchuan peat cellulose d18O record shows that the evolutional process of CCZ occurred generally in the warmer climatic condition on centennial timescale. The Xia Dynasty, the first dynasty in the Chinese history, was established at 2070 BC that just points to a turning point from a decreasing to an increasing of temperature. In the warmer and drier Shang Dynasty ancient China completed transition from the Neolithic to Bronze Age, and created the Oracle bone script. The following around 800-year also was in the warmer and drier climate. Occurrence of the different philosophies, including Confucianism, Taoism, Legalism and Mohism, had laid the foundation for CCZ. In the Qin and Han Dynasties roughly corresponding to the Roman Warmer Period the unification of both Chinese characters and metrology had been completed. The world's first movable type technique, compass and powder used in war occurred in the Song Dynasty corresponding to the Medieval Warm Epoch of Europe. Abrupt climatic deterioration seems to be often liked to agricultural failures and instability in the ancient society. The peat record indicates a widespread climate abnormality from about 3000 to 2000 BC corresponding to the archaeological Longshan era. Both the Hongshan culture in the northern China and the Liangzhu culture in the lower reaches of Yangtze River collapsed to around 2200 BC. However the Yellow River basin culture in the late Longshan era had obviously contained the characteristics of both the nomadic culture and the Yangtze River basin culture, and eventually was developed into the unified CCZ marked by the establishment of the Xia Dynasty. NORTH ANDEAN FOREST DYNAMICS MIMICS GREENLAND ICE CORES: CHANGING VEGETATION, LAKE-LEVELS, GEOCHEMISTRY, AND SEDIMENT FLUX AT w50-YR RESOLUTION DURING THE LAST 284 KA Henry Hooghiemstra. University of Amsterdam / Institute for Biodiversity, Netherlands E-mail address: [email protected]
Pleistocene climate change is well documented in the marine LR04 benthic d18O stack record which serves as the standard for climate variability. Ice cores record climate change of the last part of the Pleistocene with stunning detail. Although land-based records of climate change often suffer from hiatuses and unsufficient time control some sedimentary basins keep archives of unprecedented high quality. Records from a new 60-m composite record from the Fúquene Basin (Colombia), reflecting the period 284-27 ka, are presented. Ca. 4600-point time series of pollen, elements and grain size fractions allow individual proxies to be interpreted in a multiproxy environment. A newly developed independent age model and correlations with marine and ice records place the evolution of Andean ecosystems in a global perspective. We compared the Fúquene record with the re-visited 2700-ka Funza-2 record form the Bogotá Basin (2100-point time series from a 586-m core). We concluded that vegetation change in the high Andes is mainly driven by obliquity (41 kyr) forcing. A modelling study showed that solar forcing alone cannot explain the observed temperature record hinting changing pCO2 is an important driver in the high tropical Andes. The life cycle of paleo-lake Bogotá is newly explored and discussed. CONTROL OF QUARRYING BY BEDROCK JOINTS Thomas Hooyer. University of Wisconsin-Milwaukee, United States E-mail address: [email protected]
The formation of overdeepened valleys and basins in glaciated terrain is the result of enhanced subglacial erosion that is likely dominated by quarrying. This process is thought to depend on slow growth of preexisting, isolated